Okay. I don't think Shinra wants to brand the insane and I don't think that getting confrontational is going to produce any kind of useful discussion. So if we wanna go down that route forget it.
I don't think anyone here is arguing that people who are in trouble or hurting shouldn't get the help they need. I also think that Constantine is right that there are now some objective measures in place to gauge severeness and type of mental illness, though my opinon is that the treatment of mental health issues is still in its infancy, only one step ahead of the neural equivalent of sawing limbs off and pouring on hot tar (I would say THAT was the Victorian/Early 20th Century era). We just don't understand the brain well enough yet to really properly analyse problems, let alone treat them meaningfully.
What I'm trying to get at is that by definition mental illness means something has gone "wrong". Now, in spite of some recent advances, I would say that we do not fully understand the human brain anything near enough to make words like "wrong" anything near to objective. We do so based on context - our social mores, historical norms, utilitarianism, etc. "Wrong" is obviously a loaded and partially subjective term. Also, it can mean wrong internally (I feel bad) or it can mean wrong from an external point of view (doesn't get along well with others).
The point being that someone who goes out and kills a large number of people who they had no previous interactions with and who (in this case and in the Norway case) are generally seen as vulnerable and blameless, is "wrong" on both points. It's wrong in every goddamned possible way. There's no "right" random killing of a bunch of children.
Separately, you can talk about military killings or whatever else, but those are at least rooted in social mores that (for good or ill) most of us have chosen to accept - or at least to not fight. We may not like killing or war personally, but we get why they happen and why people participate in them. To conflate the two as "it's all just killin'" or whatever, masks the causes of both to the detriment of any kind of useful problem solving.
EDIT: Warning - while you were typing 3 new replies have been posted. You may wish to review your post.
Okay, maybe you guys do want to fight like idiots after all. NEVER MIND.